• Hardware

  • amp outs, which is – which is +?

In my setup, I have a BELA and a computer, both with two speaker chassis.
I'd like to plug speakers consistently, i.e. I'd like to know which Pin on the BELA speaker outs is + and which one -. Can you help me out? This doesn't tell...

Pin 2 of each connector (i.e. the ones facing the edge of the board, by the L and R labels) is positive, in the sense that the signal there will be in phase with the line output.

That said, in practice it probably doesn't matter too much as long as both speakers are connected in the same direction. And for future reference, each amp IC contains two amplifiers in a bridged configuration, so both output pins are active, with opposite phase, meaning neither pin can be connected to system ground.

    andrew thanks!
    I also have some weird conneciton difficulty with tweeters (might be the tweeters though): If I connect them to the outs, the amps get pretty hot pretty fast, whereas my MAX89306-based adafruit amp does not mind at all and just lets me use them... you have an idea on this?

      The power amps expect an 8ohm load, what is the impedance of your tweeters?

      that's the weird part about it... when I measure them (resistance), they have ininite resistance...

      Hmm they should normally read a few (2-8) ohms from a multimeter, unless they have a built-in series capacitor?

      yepp, that's what I thought... I cannot tell about the cap without breaking one of them... which would be a shame...
      but I think I'll anyhow use separate amps now, the built-in ones are quite little power...

      Yeah, that's about as much power you can get out of a 5V-powered AB amplifier on a 8ohm load.
      Getting more power would require a step-up power supply.